Halftone image recording apparatus and method based on first and second timing signals chosen from a plurality of synchronized clocks

Abstract

A half-tone image recorder in which input digital data is represented by a plurality of bit data for each pixel. A data conversion device outputs digital data indicative of a recording-start position and a recording-end position, based on the input digital data. A recording device such as a laser printer records an image in accordance with the output digital data from the data conversion device. The data conversion device controls a first value of the digital data indicative of the recording-start position and a second value of the digital data indicative of the recording-end position so as to change a black-area growing direction within one pixel in the recorded image. This results in the recordation of a high-quality half-tone image without conspicuous vertical stripes and without conspicuous white stripes in the main-scanning direction of the recording device due to pitch irregularity.

What is claimed is: 
     
       1. An image recording apparatus comprising: input means for inputting digital image data in which one pixel is represented by a plurality of bit data;   data conversion means for outputting digital data indicative of a recording-start position and digital data indicative of a recording-end position once for each pixel, based on the digital image data input by said input means; and   recording means for recording an image in accordance with the digital data output by said data conversion means,   wherein said data conversion means outputs each of the digital data indicative of the recording-start position and the digital data indicative of the recording-end position once for said each pixel, and controls a first value of the digital data indicative of the recording-start position and a second value of the digital data indicative of the recording-end position so as to change a solid black-area growing direction within one pixel in the image recorded by said recording means, and   wherein said recording means records the solid black area having an area fixed by the recording-start and recording-end positions, as one pixel of the image.   
     
     
       2. The image recording apparatus according to claim 1, wherein said data conversion means controls said first value of the digital data and said second value of the digital data so as to change the solid black-area growing direction within one pixel alternately by recording line. 
     
     
       3. The image recording apparatus according to claim 1, further comprising generation means for generating a plurality of clocks having phases shifted by a predetermined amount from each other, wherein said recording means records the image in accordance with the digital data output by said data conversion means and the plurality of clocks generated by said generation means.   
     
     
       4. The image recording apparatus according to claim 3, wherein said generation means generates the plurality of clocks by passing one reference clock to a delay-circuit network comprising a plurality of gates, and the delay-circuit network is constituted as one IC package. 
     
     
       5. An image recording apparatus comprising: input means for inputting image density data indicative of image density;   setting means for setting an area having a plurality of pixels, in the image density data input by said input means;   addition means for adding a plurality of data having different values to respective image density data of the plurality of pixels within the area set by said setting means, and for outputting image density data indicative of the addition; and   recording means for controlling a dot diameter, based on the image density data output by said addition means, and recording an images,   wherein a sum of the values of the plurality of data added to the respective image density data of the plurality of pixels by said addition means is zero, thus a sum of the image density data of the plurality of pixels within the area and the sum of the image density data within the area output by said addition means correspond with each other.   
     
     
       6. The image recording apparatus according to claim 5, wherein if the area set by said setting means is a black area, said addition means does not add the plurality of data having different values to the image density data input by said input means. 
     
     
       7. The image recording apparatus according to claim 5, wherein if the area set by said setting means is a low-density area or a high-density area, said addition means does not add the plurality of data having different values to the image density data input by said input means, and wherein if the area set by setting means is an intermediate-density area, said addition means adds the plurality of data having different values to the image density data input by said input means. 
     
     
       8. An image recording apparatus comprising: input means for inputting image data;   recording means for recording an image based on the image data input by said input means; and   pitch-irregularity improvement means for improving degradation of image quality due to pitch irregularity upon recording the image by said recording means,   wherein if the image data input by said input means is low-density data or high-density data, said pitch-irregularity improvement means does not perform pitch-irregularity improvement processing, while if the image data is intermediate-density data, said pitch-irregularity improvement means performs pitch-irregularity improvement processing.   
     
     
       9. An image recording apparatus comprising: input means for inputting image data;   recording means for recording an image based on the image data input by said input means; and   pitch-irregularity improvement means for improving degradation of image quality due to pitch irregularity upon recording of the image by said recording means,   wherein if the image data input by said input means is binary image data representing a character or figure, said pitch-irregularity improvement means does not perform pitch-irregularity improvement processing, while if the image data is multi-value image data representing a half-tone image, said pitch-irregularity improvement means performs pitch-irregularity improvement processing.   
     
     
       10. An image recording method comprising: an inputting step of inputting digital image data in which one pixel is represented by a plurality of bit data;   a data conversion step of outputting digital data indicative of a recording-start position and digital data indicative of a recording-end position once for each pixel, based on the input digital image data; and   a recording step of recording an image on a recording device in accordance with the output digital data,   wherein said data conversion step outputs each of the digital data indicative of the recording-start position and the digital data indicative of the recording-end position once for said each pixel, and controls a first value of the digital data indicative of the recording-start position and a second value of the digital data indicative of the recording-end position so as to change a solid black-area growing direction within one pixel in the recorded image, and   wherein said recording step records the solid black-area having an area fixed by the recording-start and recording-end positions, as one pixel of the image.   
     
     
       11. An image recording method comprising the steps of: inputting image density data indicative of image density;   setting an area having a plurality of pixels, in the input image density data;   adding a plurality of data having different values to respective image density data of the plurality of pixels within the set area; and   controlling a dot diameter for image recording, based on image density data indicative of the addition and recording an image,   summing of the values of the plurality of data added to the respective image density data of the plurality of pixels in said addition step resulting in a zero value wherein summing of the image density data of the plurality of pixels within the area and summing of the image density data within the area output by said addition means corresponds with each other.